Design and synthesis of conformationally constrained tri-substituted ureas as potent antagonists of the human glucagon receptor.

A series of conformationally constrained tri-substituted ureas were synthesized, and their potential as glucagon receptor antagonists was evaluated. This effort resulted in the identification of compound 4a, which had a binding IC50 of 4.0 nM and was shown to reduce blood glucose levels at 3 mg/kg in glucagon-challenged mice containing a humanized glucagon receptor.